Vbox crashes my whole system

Description

After installing Vbox and guest additions on my Windows XP it request reboot of the system. After the reboot my system cant boot up properly. i.e. after the windows boots up the mouse pointers goes to the left bottom corner of the screen and stays there. When i move the mouse the pointer moves for a second and again goes to the left bottom corner.I can't even click the login name on the boot screen. I try to boot the Windows XP in safe mode and againt the same happens, i even tried to boot in Safe mode with Command prompt, and its also the same.
This happened to me 3 times till now, even with different versions of Vbox, and i had to format and reinstall Windows XP. This is the 4th time the same problem appears and i dont want to format again because i'll lose some important work.
If it means something for u i have Dell Inspiron 1520 Notebook (Intel Core 2 Duo, 2GB RAM, 120GB WD HDD).
PLEASE HELP ME WITH THIS ISUE, IT REALLY IMPORTANT FOR ME.
This is my mail address: togenx@…
Thanks

I HOPE TO HEAR FROM U.

Change History

Yes i did :( , and i shouldn't do that right?
I think that after installing the guest additions on the XP host it messes up something with the Mouse and/or keyboard.
So is there a way to receover my XP instalation witout formating?
I have openSuse installed on other partition so i have access to the partition where Windows is installed.